Function checkWhen

checkWhen(
when: string | (() => boolean) | undefined,
conditions: Map<string, boolean>,
): boolean
Evaluate a when condition — either a function () => boolean, a string referencing a named condition, or undefined (always passes).

When when is a string and the named condition has not been registered, this throws a descriptive error so the missing addCondition(id, ...) call is caught immediately at key-press time.
Parameters
- when: string | (() => boolean) | undefined
  The condition to evaluate.
- conditions: Map<string, boolean>
  The conditions map from the pipeline context.
Returns boolean
The resolved boolean value of the condition.
Throws
If when is a string referencing an unregistered condition.
Example
```
const conditions = new Map([['isEditing', true]]);

checkWhen('isEditing', conditions);   // true
checkWhen(() => false, conditions);   // false
checkWhen(undefined, conditions);     // true (no condition = pass)
```
- Defined in src/keyboard-engine/src/checkWhen.ts:23